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[en] The authors analyze the epithermal and thermal portions of the energy spectrum of neutrons in the lattices of water-cooled, water-moderated power reactors based on experimentally determined spectral indices of eight isotopes. The obtained values of the thermal spectral indices are compared with those calculated by the programs YAM(A) (Monte Carlo method), THERMOS, and the variant program POP. The data obtained with the first two programs agree fairly well and are in line with the experimental data; the POP program predicts excessively rigid spectra. It has been established experimentally that the neutron flux in the epithermal region falls away more slowly than the 1/E-dependence

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[en] Experimental methods and results of measuring the reaction rate space distribution in a homogeneous elementary uranium-water cell and in cells near the heterogeneities of a B₄C rod,air and water void types are described. Investigations were conducted in a subcritical uranium-water WWER bench by activation technique with subsequent irradiated uranium foil detector separation into parts using a coordinate electric-spark tool. The induced foil γ-activity was measured by γ-spectrometry method in two Li-drifted Ge semiconductor detectors. Analysis of the distribution determination errors as well as results of evaluating the fuel element temperature with regard to experimentally produced energy release irregularity over the fuel element radius are presented. The investigations have shown that the methods applied are sensitive to heterogeneities creating over 3.5% pertubations in ²³⁸U(n, γ)-reaction rate distribution and over 2.5% ones-in ²³⁵U(n, f)-reaction distribution. The maximum asymmetry in plutonium accumulation rate distribution in the fuel ent (up to 20-30%) is observed near the air and water voids. The maximum asymmetry in ²³⁵U fission rate distribution in the fuel element (up to 10%) is observed near the absorbing element

[en] The analysis of activities carried out in this country and abroad on a complex solution of principal problems of nuclear power advance. Demonstration of the potentiality of the above problems solution on the basis of conventional reactor plant development (light water cooled reactors and BN-type fast reactors) within the framework of nuclear fuel cycle using uranium-235, plutonium and uranium-233. 28 refs.; 1 fig.; 8 tabs

[en] This paper presents experimental investigations for the determination of n,γ(U-238) and n,f(U-235) reaction rates in an elementary cell near the core performed at BOL. On the basis of this information the PU-239 buildup and U-235 fission rate were calculated and used as input in 2 DT calculations. These resulted in a 200 deg. C central temperature decrease (at about 448 W/cm MLHR). (author). 2 refs, 5 figs

[en] Series of investigations into the current of rhodium direct charging detectors (DCD) of inside reactor control systems and their connection with the release of energy in the nearest surrounding of the WWER-1000 fuel assembly model were carried in the RRC Kurchatov Institute in 2001 - 2002. Experiments were performed on the critical testing unit SK-fiz, calculations - by the precision program MCU-REA/2 using Monte Carlo method. Reference experimental-calculation procedure for the determination of connection of DCD current with the number of divides in six neighboring fuel elements and fuel assemblies was described, effects depending on DCD location in the center and fourth line of the fuel assembly were studied, experimental and calculation data were compared